Platen locking device in powdered material compacting presses

ABSTRACT

In a press for compacting powdered materials into shaped articles between upper and lower punches within a cavity of a die platen, platen locking devices are provided to hold or lock a movable platen during the compacting process. Each of the locking devices comprises a wedge driving member depending from the movable platen and having a pair of downwardly converging wedging bottom end faces adapted to cooperate with a pair of oppositely arranged wedge members slidably carried on a stationary platen below said platen. The wedge members are urged toward each other by means of springs and are adapted to be locked in mutually closest positions to prevent downward movement of the wedge driving member by means of a locking key engaging or entering from below aligned bottom grooves in the wedge members. Unlocking of the device is effected by lowering the locking key to disengage it from said grooves in connection with a predetermined downward movement of the die platen above the movable platen.

United States Patent Hara et al. {4 1 Jan. 118, 11072 [541 PLATEN LOCKING DEVICE IN 3,460,202 8/1969 Graf et a1. ..18/16.7 x POWDERED AT COMPACTING 3,464,089 9/1969 Smith ..18/16.7

PRESSES Primary ExaminerJ. Howard Flint, Jr. Attorney-Robert E. Burns and Emmanuel J. Lobato [5 7] ABSTRACT In a press for compacting powdered materials into shaped articles between upper and lower punches within a cavity of a die platen, platen locking devices are provided to hold or lock a movable platen during the compacting process. Each of the locking devices comprises a wedge driving member depending from the movable platen and having a pair of downwardly converging wedging bottom end faces adapted to cooperate with a pair of oppositely arranged wedge members slidably carried on a stationary platen below said platen. The wedge members are urged toward each other by means of springs and are adapted to be locked in mutually closest positions to prevent downward movement of the wedge driving member by means of a locking key engaging or entering from below aligned bottom grooves in the wedge members. Unlocking of the device is effected by lowering the locking key to disengage it from said grooves in connection with a predetermined downward movement of the die platen above the movable platen.

12 Claims, 10 Drawing Figures I7 1 l2 I6 1 I4 3? PATENIED JAN? 8 1972 SHEETSUF? F I G. 5

5 ua 6 4 O 6 4 I a N O n I! b w M M M PATENTFLUJAN? 8 m2 3.635.617

SHEET 6 BF 7 FIG.6

BACKGROUND OF THE INVENTION This invention relates to powdered material compacting presses and more particularly to a device for locking and unlocking a set of platens of a press for compacting powdered materials into shaped solid articles within a die between upper and lower punches.

Compacting presses of the above-stated type wherein powdered materials, such as powdered metals, iron oxide, or ceramic materials, are formed or compacted into shaped articles by means of a die or die platen, an upper movable punch and a lower stationary punch, the punches cooperating in the cavity of the die, are known.

In such a type of compacting press, the formed article which has been compacted on the stationary lower punch is caused to be exposed, after the upper movable punch has been raised off the article, by lowering the die or die platen to the level at which the upper surfaces of the die platen and the lower punch are substantially flush with each other. Once the article is thus exposed, it can be removed out of the press by horizontally sliding it on and along the upper surfaces of the platen and punch, provided that the article has a planar bottom surface.

However, in the case where the article formed has a plurality of bottom surfaces of different levels, for example, bottom surfaces of stepped configuration, the lower stationary punch must have a correspondingly stepped configuration, and it is impossible to remove the article out of the press by horizontally sliding it on and along the upper surfaces of the die platen and the lower punch, even if the die platen is displaced downward.

In view of this difficulty, there has been proposed and wide ly used a compacting press which comprises, in addition to the movable die platen and the stationary lower punch, at least a movable lower punch which is carried on a movable platen and is capable of being displaced relative to the stationary lower punch. These stationary and movable lower punches cooperate to form combined lower punches providing a punching face having a stepped configuration in the phase of compacting operation of the press. After the article is given a stepped bottom configuration, the movable die platen and the movable lower punch are lowered to the level at which the upper surfaces of the die platen and the movable lower punch are flush with the upper surface of the stationary lower punch. Thus, it becomes possible to remove the formed article by horizontally sliding it in the press.

It is to be noted that in this case the movable lower punch must be held or locked stationary until the compacting process has been completely finished, but the same punch must be made free or unlocked after the compacting process so that it can be lowered relative to the stationary lower punch in order to provide the flush relationship between the upper surfaces of both the movable and stationary lower punches.

For these purposes, conventional compacting presses are provided with downwardly projecting rods on the bottom surface of a platen rigidly carrying thereon the movable lower punch, each of these rods being formed at the bottom end thereof with an inclined face which cooperates with a wedge member slidable on the upper surface of a stationary platen disposed directly below the above-mentioned platen and carrying thereon the stationary lower punch. The wedge member is moved or slid on the stationary platen to engage or act on the inclined bottom face of the rod so that the movable platen carrying thereon the movable lower punch can be held stationary or locked against the downwardly directed compacting force exerted by the upper movable punch.

In such a type of compacting press, however, since the wedge member acts on the downwardly projecting rod only from one side thereof, the downwardly directed compacting stroke of the upper punch naturally causes the wedge member to exert a sidewise force on the rod with a resultant undesirable bending of the rod accompanied by undue stresses in the rod and platens. It will readily be apparent that such undue stresses may cause inclination of the vertical axes of the punches, platens and so on and may impair the accuracy of the press.

SUMMARY OF THE INVENTION In view of the foregoing, it is a main object of this invention to provide a novel and improved powdered material compacting press of the above-stated type wherein bending of the rod and undue stresses in the platens and so on are eliminated.

Another object of this invention is to provide an improved powdered material compacting press of the above-stated type wherein the platen locking device includes therein a pair of symmetrically or oppositely arranged wedge members which exert only centripetal forces in the locking device whereby sidewise forces in the locking device cancel each other.

Still another object of this invention is to provide an improved powdered material compacting press of the abovestated type wherein the locking operation of the platen locking device is reliable.

A further object of this invention is to provide an improved powdered material compacting press of the above-stated type wherein the platen locking device is capable of being automatically unlocked when a platen immediately above the platen to which the locking device belongs has been moved downward a predetermined distance to expose a compacted article.

An additional object of this invention is to provide an improved powdered material compacting press wherein operational adjustment of the platen locking devices can be easily made.

Briefly stated, the powdered material compacting press of this invention is of the type comprising a series of horizontal platens arranged in vertically spaced-apart parallel relationship and vertically movable relative to each other, one of said platens having a die cavity and the remainder carrying thereon punches cooperating with said die cavity to form an article, and platen locking devices which lock some of said platens against compacting force in the compacting process. In ac cordance with the improvement of this invention, each of the platen locking devices comprises a wedge driving member depending from the lower surface of a platen except the uppermost and lowermost platens and formed at the bottom end thereof with a pair of symmetrical wedging end faces of opposite inclinations, a pair of wedge members having respective wedge surfaces associated with said wedging end faces on said wedge driving member and disposed symmetrically with respect to the vertical axis of said wedge driving member on the platen immediately below the platen from which said wedge driving member projects, said wedge members being horizontally slidable toward and away from each other, resilient means urging the wedge members toward each other into a condition where the wedge members engage each other and lie directly below said wedge driving member, means for locking said wedge members in said condition so that the wedge members can resist the wedging forces exerted by said wedge driving members to prevent the latter from moving downward relative to the wedge members, and means rcspon sive to a predetermined amount of descending movement of the platen located immediately above the platen from which said wedge driving member projects to unlock said wedge member locking means, thereby permitting said wedge members to be separated from each other under the wedging action of said wedge driving member so as to allow the platen carry ing the latter member to descend relative to the platen immediately below.

The foregoing objects and other objects of this invention as well as the characteristic features of the invention will become more apparent from the following detailed description and appended claims when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a fragmentary vertical section of a powdered material compacting press according to this invention, the press being in an operational phase in which a shaped article has just been compacted;

FIG. 2 is a view similar to FIG. 1 but showing another operational phase in which the shaped article has been partly exposed;

FIG. 3 is a view similar to FIG. 1 but showing a further operational phase in which the shaped article has been completely exposed;

FIG. 4 is an enlarged fragmentary section showing a platen locking device employed in the press shown in FIGS. 1 through 3, the locking device being shown in the operational phase corresponding to that of FIG. 1;

FIG. 5 is a view similar to FIG. 4 but showing the locking device in the operational phase corresponding to that of FIG. 2;

FIG. 6 is a view similar to FIG. 4 but showing the locking device in the operational phase corresponding to that of FIG.

FIG. 7 is a plan view showing a pair of wedge members and associated springs;

FIG. 8 is a section taken along the line VIII-VIII of FIG. 7;

FIG. 9 is a front elevation ofa locking key member; and

FIG. 10 is a side elevation of the locking key member.

DETAILED DESCRIPTION Referring now to the drawings, particularly to FIGS. 1 through 3 thereof, the powdered material compacting press shown therein is generally designated by reference numeral 2.

The compacting press 2 comprises an uppermost movable die platen 3, an intermediate movable platen 4, and a lowermost stationary platen 5 rigidly secured on a stationary frame 6 of the press by any suitable means.

The uppermost movable die platen 3 is rigidly carried on the tops of columns 7 located at four corners of the platen 3 and passing downwardly through the intermediate movable platen 4 and the lowermost stationary platen 5 to terminate on and be fixed to a yoke 8 having a bottom groove 9 adapted to be engaged with an end of a drive means which may be a suitable link mechanism driven by a prime mover or a piston rod of a hydraulic piston-cylinder assembly. The columns 7 are capable of vertical movement relative to the intermediate platen 4 and the lowermost platen 5 by means of the drive means through the intermediary of the yoke 8.

The die platen 3 is formed with a vertically extending through hole 10 forming the internal cavity of a forming die.

A movable lower punch 12 is rigidly secured to the intermediate platen 4 and slidably fitted in the hole 10 at its upper portion. Within a hollow bore 13 of the movable lower punch 12, there is disposed a stationary lower punch 14 which is slidably fitted within the bore 13 and rigidly secured to the lowermost platen 5. The uppermost die platen 3 is provided with pusher rods 16 screwed into the platen 3 and secured in position by nuts 17 to project downward from the bottom surface of the platen.

From the yoke 8, a mandrel 18 extends upward through an interior bore 19 in the stationary lower punch 14.

Above the uppermost die platen 3, there is disposed an upper punch holder 20 holding an upper punch 21 and adapted to be driven upward and downward in a conventional manner. The upper punch 21, in its downwardly displaced operative position as shown in FIG. I, is brought into the die cavity 10 to press and form therein an article 22 in cooperation with the die platen 3 and lower punches I2 and 14.

The above-described construction of the compacting press is known, and the press operates as follows:

In the phase of operation as shown in FIG. 1, the article 22 has just been pressed or compacted, the article being of the shape having an annular peripheral flange on the upper half of a main cylindrical body.

In the next phase of operation as shown in FIG. 2, the uppermost die platen 3 is lowered by means of the drive through the yoke 8 and the columns 7 so that the upper surfaces of the die platen 3 and the movable lower punch 12 are made substantially flush with each other.

In this condition, the flange of the compacted article 22 is almost fully exposed on the upper surface of the lower punch 12 as is clearly shown in FIG. 2.

It should be noted that in this phase of operation, the bottoms of the pusher rods I6 are slightly spaced apart upward from the upper surface of the intermediate platen 4.

In a still further phase of operation shown in FIG. 3, the die platen 3 is further moved downward so that the bottom faces of the pusher rods .16 abut against the upper surface of the intermediate platen 4. The further movement of the die platen 3 causes the intermediate platen 4 to be moved downward relative to the stationary lower punch 14 with the result that the upper surface of the movable lower punch 12 on the intermediate platen 4 is caused to be brought into flush relationship with the upper surface of the stationary lower punch 14. It should be noted that under such a condition the article 22 is fully exposed on the lower punches and may be easily taken out of the press by sliding it laterally.

After the article is taken out, the platens of the press are brought again into the condition of FIG. 1 and the abovedescribed operation is repeated.

It will be apparent that in the phase of operation shown in FIG. 1, the movable lower punch 12 must be kept or locked in the axial position shown in the figure against the downward force of the upper punch, in which position the upper surface thereof is slightly raised relative to that of the stationary lower punch 14 to provide an annular space or cavity in which the flange of the article is to be formed. For this purpose the inter mediate platen 4 carrying the movable lower punch 12 must be rigidly and firmly supported or locked by platen locking devices L against the downwardly directed compacting force of the upper punch 21.

An example of the platen locking device L in accordance with this invention is shown in detail in FIGS. 4 through 10, inclusive.

Referring to FIG. 4 showing an enlarged view of the platen locking device L which is in the condition corresponding to the operational condition of FIG. 1, the intermediate platen 4 as previously described has rigidly secured thereto a downwardly extending wedge driving member 30, which is made up of a cylindrical member 30a and a wedging tip 30b rigidly secured to each other by any suitable means. The cylindrical member 3011 has an upper portion of reduced diameter fitting snugly in an opening 4a cut in the intermediate platen 4. The member 30a is formed with a vertically extending through hole including a reduced diameter hole 310 and an enlarged diameter hole 31b in the lowermost end of which is fitted a cylindrical portion 32 on the wedging tip 30b.

Through the wedging tip 30b there is formed a vertically extending hole 33. An unlocking rod 34 extends through the holes 31a, 31b and 33 and has an abutment flange 34a. Between the flange 34a and the cylindrical portion 32, there is disposed a compression coil spring 35 urging the unlocking rod 34 upward. In the normal condition of the rod 34, its flange 34a abuts against the shoulder between the holes 3111 and 31b as shown in FIG. 4. It is to be noted that the top of the rod 34 is provided with a bolt 37 screwed into the rod and projecting above the upper surfaces of the cylindrical member 3011 and the platen 4. The length by which the bolt 37 projects may readily be adjusted by turning the bolt and tightening a nut 38. It is also to be noted that the lower part of the rod 34 extends downward beyond the bottom of the wedging tip 30b which has a pair of symmetrical wedging end faces 40a and 40b of opposite inclinations converging downward.

As shown in FIG. 4, the stationary lowermost platen 5 has a stepped opening 50 in which a female screw member 42 of a stepped configuration is rotatably received. The screw member 42 is formed with internal threads 42a with which outer threads 430 on a supporting base 43 is in mesh. It will be noted that the supporting base 43 may be adjusted in its vertical position relative to the platen 5 by turning the member 42 by suitable means. The supporting base is formed with a vertically extending hole 43b in which is disposed a locking key member 44 having a cylindrical body 44a and a horizontally elongated head 44b as shown in FIGS. 9 and I0, said key member being urged upward by a compression coil spring 45.

On the upper surface of the supporting base 43, there is rigidly mounted a hollow wedge guide generally designated by reference numeral 46. The wedge guide 46 is made up of a bottom plate 46a rigidly secured to the supporting base 43, a top plate 46b having an upstanding hub 48c, and said plates 46d. On the inside walls of the bottom and top plates 46a and 46b and of the hub 46c, antifriction linings 47a, 47b and 460 may be provided for the purpose of reducing friction.

The bottom plate 46a has rigidly secured thereto a guide bar 49 slidably fitted within a guide hole 50 cut through the stationary platen 5.

Within the bore of the hub 46c of the wedge guide 46 is slidably fitted the wedge driving member 30 as shown in FIG. 4. The wedging end faces 40a and 40b on the wedge driving member 30 cooperate with and are in contact with wedge surfaces 52 and 53 formed on wedge members 54 and 55, respectively. The wedge surfaces 52 and 53 have inclinations corresponding to those of the wedging end faces 40a and 48b.

The wedge members 54 and 55 are slidable horizontally on the linings 47a and 47b in a symmetrical manner with respect to the vertical axis of the platen locking device L or with respect to the axis of the unlocking rod 34. The wedge members 54 and 55 are urged toward each other by means of compression springs 56 and 57 as is most clearly shown in FIG. 7.

The internal side surface of one wedge member 54, opposing the internal side surface of the other wedge member 55, is formed with a recess 54a, while the internal surface of the member 55 is formed with a projection 55a which is of a configuration complementary to the recess 54a. The projection 55a is formed with a vertical groove 60 for accommodating the unlocking rod 34.

The wedge member 54 is provided in the bottom surface thereof with a pair of lateral grooves 61 while the wedge member 55 is provided in the bottom surface thereof with a lateral groove 62. These grooves 61 and 62 are in lateral alignment with each other when the wedge members 54 and 55 are moved closest toward each other as shown in FIGS. 7 and 8. The wedge members 54 and 55 are provided with respective bottom guide grooves 63 and 64 extending perpendicularly to said grooves 60 and bl, as shown in FIGS. 4 and 8. Pegs or pins 65 and 66 secured on the supporting base 43 and passing through the bottom plate 46a into the grooves 63 and 64 serve to guide the wedge members in the sliding movement thereof.

ln the operative condition of the locking device L as shown in FIG. 4, the head 44b of the locking key member 4 is in engagement with the bottom grooves 6t and 62 and is in abutment with the bottom end of the unlocking rod 34. Under such a condition, the wedge members 54 and 55 are locked in the mutually closest innermost position and cannot be separated from each other.

The operation of the platen locking devices L in relation to the operation of the press is as follows.

In the condition shown in FIG. 4 corresponding to that of FIG. I, the wedge members 54 and 55 are in the locked position. Therefore, when the compacting force exerted by the downstroke of the upper movable punch 21 is transmitted via the movable lower punch l2 and the intermediate platen 4 to the wedge driving member 30, the locked pair of wedge mem' bers 54 and 55 can resist the downwardly directed force of the member 30. Accordingly, the compacting process can be carried out effectively.

In the condition of FIG. 5 corresponding to that of FIG. 2, the bottom end of the pusher rod 16 is brought into engagement with the bolt 37 on the top of the unlocking rod 34 and is depressing the rod 34 and locking key 44 slightly downward against the forces of the springs 35 and 43. It will be noted that, in this condition, the head 44b of the locking key member 44 has been completely disengaged from the bottom grooves fill and 62 in the wedge members 54 and 55V Therefore, the members 54 and 55 are in unlocked condition but are retained in the mutually closest positions as shown by the force of the springs 56 and 57.

In the next phase of operation as shown in FIG. 6 cor responding to that of FIG. 3, the bottom end of the pusher rod 16 has advanced or descended to the position where it is in full engagement with the upper surface of the wedge driving member 30 and has depressed the latter a considerable distance, while the unlocking rod 34 has been depressed slightly relative to the member 30 and has also been moved downward a considerable distance with the member 30. It will be noted that the locking key member 44 has been retracted completely into the hole 43b.

In the course of the downward movement of the wedge driving member 30, the pair of wedges 54 and 55 are subjected to the wedging action of the end faces 40a and 4b and separated from each other, sliding along the linings 47a and 47b against the compressive force of the springs 56 and 57, since these wedges 54 and 55 are no longer locked by the locking key 44. It will be apparent that the downward movement of the wedge driving member 30 will also enable downward movement of the intermediate platen 4 to the position indicated in FIG. 3 at which the article 22 produced is completely free from the lower movable punch 12.

After the compacted article 22 has been removed, the intermediate and die platens 4 and 3 return to their original positions shown in FIG. 1. When the intermediate platen 4 is lifted by spring force to the original level, the wedge members 54 and 55 are freed from the wedging action by the member 30 and permitted to move inwardly to the original mutually closest position. Thereafter, when the bottom of the pusher rod 16 leaves the head of the bolt 37 because of further upward movement of the die platen 3, the locking key member 44 is allowed to enter or engage the bottom grooves 63 and d4 of the wedge members 54 and 55, and the original locked condition of the wedge members is reestablished. The press is thus ready for the next compacting operation.

It should be understood that, in accordance with this inven tion, since the the wedge members are disposed as a pair in symmetrical relationship with respect to the vertical axis of the platen locking device, the device is subjected to symmetrical force with respect to its vertical axis in supporting or propping up the platen and, therefore, is mechanically stable and durable.

Although a preferred embodiment including one intermediate platens has been shown and described, it will be un' derstood that the invention is equally applicable to compacting presses having two or more intermediate platens. In such presses, the platen locking device according to the invention may be installed for each of the intermediate platens.

We claim:

ll. In a powdered material compacting press of the type comprising a series of a horizontal platens arranged in vertically spaced-apart parallel relationship and adapted to be vertically movable relative to each other, one of said platens having therein a die cavity and remaining platens carrying thereon punches from cooperating with said cavity to form an article within said die cavity, and platen locking devices which lock some of said platens against compacting force in the compacting process, the improvement wherein said each of said platen locking devices comprises a wedge driving member projecting downward from the lower surface of a platen except the uppermost and lowermost platens and formed at the bottom end thereof with a pair of symmetrical wedging end faces of opposite inclinations, a pair of wedge members having a respective wedge surfaces associated with said wedging end faces on said wedge driving member and disposed below the latter member symmetrically with respect to the vertical axis of the member on the platen immediately below the platen from which said wedge driving member projects, said wedge members being horizontally slidable toward and away from each other, resilient means urging the wedge members toward each other into a condition where the wedge members engage each other and lie directly below said wedge driving member, means for locking said wedge members in said condition whereby the wedge members can resist the wedging forces exerted by said wedge driving member to prevent the latter from moving downward relative to the wedge members, and means responsive to a predetermined amount of descending movement of a platen located immediately above the platen from which said wedge driving member projects to unlock said wedge member locking means, thereby permitting said wedge members to be separated from each other under the wedging action of said wedge driving members so as to allow the platen from which the latter projects to descent relative to the platen immediately below.

2. In a powdered material compacting press of the type comprising a movable upper most die platen having a vertical through hole defining a die cavity, a movable intermediate platen rigidly carrying thereon a movable lower punch of a cylindrical form slidably received within said die cavity, a lowermost stationary platen rigidly carrying thereon a stationary lower punch slidably fitted within the bore of said cylindrical movable lower punch, a movable upper punch adapted to be introduced into said die cavity from above to cooperated with said lower punches to compact the powdered materials within said cavity into a shaped article, means driving said upper punch, and platen locking devices disposed between said intermediate and lowermost platens and effective to prevent, in a locked position, downward movement of said intermediate platen to resist the downward compacting force exerted by said movable upper punch, and to allow, in an unlocked position, downward movement of said intermediate platen to expose the shaped article, the improvement wherein each of said platen locking devices comprises a wedge driving member projecting downward from the lower surface of said intermediate platen and formed at the bottom end thereof with a pair of symmetrical wedging end faces of opposite inclinations, a pair of wedge members having on the upper surfaces thereof respective wedge surfaces associated with said wedging end faces on said wedge driving member and disposed below said wedge driving member symmetrically with respect to the vertical axis of said wedge driving member on said stationary lower most platen, said wedge members being horizontally slidable toward and away from each other, resilient means urging the wedge members toward each other to positions at which the wedge members lie directly below said wedge driving member, means for locking said wedge members at said positions so that the latter members can resist the wedging forces exerted by said wedge driving member to prevent the latter from moving downward, and means responsive to a predetermined amount of descending movement of the uppermost platen to unlock said wedge member locking means, thereby permitting said wedge members to be separated from each other under the wedging action of said wedge driving member thereby to allow the intermediate platen to descend toward the lowermost platen 3. The powdered material compacting press as claimed in claim 1, wherein said symmetrical wedging end faces on the bottom end of the wedge driving member extend downwardly and inwardly in convergent relationship to each other.

4. The powdered material compacting press as claimed in claim 1, wherein said wedge members are slidably enclosed in a hollow wedge guide which has an upwardly opening upright hub slidably receiving said wedge driving member.

5. The powdered material compacting press as claimed in claim 1, wherein one of said wedge members is formed with at least a side recess and the other of said wedge members is formed with at a side projection complementary to said side recess, said recess and projection engaging each other at the closest positions of the wedge members.

. The powdered material compacting press as claimed in claim 1, wherein said resilient means are a pair of compression springs connecting both wedge members.

7. The powdered material compacting press as claimed in claim 4, wherein said wedge guide is rigidly secured to a supporting base carried on the platen, said supporting base being adjustable in its vertical position relative to the platen.

8. The powdered material compacting press as claimed in claim 1, wherein said means for locking the wedge members comprises bottom grooves cut in the bottoms of said wedge members and adapted to be aligned when the wedge members engage each other at the closest positions thereof, and locking key members resiliently urged to engage the aligned grooves in the bottoms of said-wedge members.

9. The powdered material compacting press as claimed in claim 7, wherein said means for locking the wedge members comprises bottom grooves formed in the bottoms of said wedge members and adapted to be aligned when the wedge members engage each other at the closest positions thereof, and locking key members disposed in a vertical bore within said supporting base and adapted to project upward into the hollow interior of said wedge guide and to engage the aligned grooves in the bottoms of said wedge members by means of the force of a spring disposed in said vertical bore.

10. The powdered material compacting press as claimed in claim I, wherein said means responsive to a predetermined amount of descending movement of the platen comprises an unlocking rod slidably passing vertically through said wedge driving member and resiliently urged upward to extend above the upper surface of the platen from which the wedge driving member projects downward, the upper end of said unlocking rod being adapted to be depressed by a platen immediately thereabove and the lower end of said unlocking rod being in connection with said means for locking the wedge member.

11. The powdered material compacting press as claimed in claim 9, wherein said means responsive to a predetermined amount of descending movement of the platen comprises an unlocking rod slidably passing vertically through said wedge driving member and resiliently urged upward to extend above the upper surface of the platen from which the wedge driving member depends, the upper end of said unlocking rod being adapted to be depressed by a platen immediately thereabove and the lower end of said unlocking rod being in abutment with the upper end of said locking key member.

12. The powdered material compacting press as claimed in claim 11, wherein said unlocking rod is resiliently urged by means of a compression spring disposed in a hollow interior of said wedge driving member and acting upward on a flange formed on said unlocking rod. 

1. In a powdered material compacting press of the type comprising a series of a horizontal platens arranged in vertically spaced-apart parallel relationship and adapted to be vertically movable relative to each other, one of said platens having therein a die cavity and remaining platens carrying thereon punches from cooperating with said cavity to form an article within said die cavity, and platen locking devices which lock some of said platens against compacting force in the compacting process, the improvement wherein said each of said platen locking devices comprises a wedge driving member projecting downward from the lower surface of a platen except the uppermost and lowermost platens and formed at the bottom end thereof with a pair of symmetrical wedging end faces of opposite inclinations, a pair of wedge members having a respective wedge surfaces associated with said wedging end faces on said wedge driving member and disposed below the latter member symmetrically with respect to the vertical axis of the member on the platen immediately below the platen from which said wedge driving member projects, said wedge members being horizontally slidable toward and away from each other, resilient means urging the wedge members toward each other into a condition where the wedge members engage each other and lie directly below said wedge driving member, means for locking said wedge members in said condition whereby the wedge members can resist the wedging forces exerted by said wedge driving member to prevent the latter from moving downward relative to the wedge members, and means responsive to a predetermined amount of descending movement of a platen located immediately above the platen from which said wedge driving member projects to unlock said wedge member locking means, thereby permitting said wedge members to be separated from each other under the wedging action of said wedge driving members so as to allow the platen from which the latter projects to descent relative to the platen immediately below.
 2. In a powdered material compacting press of the type comprising a movable upper most die platen having a vertical through hole defining a die cavity, a movable intermediate platen rigidly carrying thereon a movable lower punch of a cylindrical form slidably received within said die cavity, a lowermost stationary platen rigidly carrying thereon a stationary lower punch slidably fitted within the bore of said cylindrical movable lower punch, a movable upper punch adapted to be introduced into said die cavity from above to cooperated with said lower punches to compact the powdered materials within said cavity into a shaped article, means driving said upper punch, and platen locking devices disposed between said intermediate and lowermost platens and effective to prevent, in a locked posiTion, downward movement of said intermediate platen to resist the downward compacting force exerted by said movable upper punch, and to allow, in an unlocked position, downward movement of said intermediate platen to expose the shaped article, the improvement wherein each of said platen locking devices comprises a wedge driving member projecting downward from the lower surface of said intermediate platen and formed at the bottom end thereof with a pair of symmetrical wedging end faces of opposite inclinations, a pair of wedge members having on the upper surfaces thereof respective wedge surfaces associated with said wedging end faces on said wedge driving member and disposed below said wedge driving member symmetrically with respect to the vertical axis of said wedge driving member on said stationary lower most platen, said wedge members being horizontally slidable toward and away from each other, resilient means urging the wedge members toward each other to positions at which the wedge members lie directly below said wedge driving member, means for locking said wedge members at said positions so that the latter members can resist the wedging forces exerted by said wedge driving member to prevent the latter from moving downward, and means responsive to a predetermined amount of descending movement of the uppermost platen to unlock said wedge member locking means, thereby permitting said wedge members to be separated from each other under the wedging action of said wedge driving member thereby to allow the intermediate platen to descend toward the lowermost platen
 3. The powdered material compacting press as claimed in claim 1, wherein said symmetrical wedging end faces on the bottom end of the wedge driving member extend downwardly and inwardly in convergent relationship to each other.
 4. The powdered material compacting press as claimed in claim 1, wherein said wedge members are slidably enclosed in a hollow wedge guide which has an upwardly opening upright hub slidably receiving said wedge driving member.
 5. The powdered material compacting press as claimed in claim 1, wherein one of said wedge members is formed with at least a side recess and the other of said wedge members is formed with at a side projection complementary to said side recess, said recess and projection engaging each other at the closest positions of the wedge members.
 6. The powdered material compacting press as claimed in claim 1, wherein said resilient means are a pair of compression springs connecting both wedge members.
 7. The powdered material compacting press as claimed in claim 4, wherein said wedge guide is rigidly secured to a supporting base carried on the platen, said supporting base being adjustable in its vertical position relative to the platen.
 8. The powdered material compacting press as claimed in claim 1, wherein said means for locking the wedge members comprises bottom grooves cut in the bottoms of said wedge members and adapted to be aligned when the wedge members engage each other at the closest positions thereof, and locking key members resiliently urged to engage the aligned grooves in the bottoms of said wedge members.
 9. The powdered material compacting press as claimed in claim 7, wherein said means for locking the wedge members comprises bottom grooves formed in the bottoms of said wedge members and adapted to be aligned when the wedge members engage each other at the closest positions thereof, and locking key members disposed in a vertical bore within said supporting base and adapted to project upward into the hollow interior of said wedge guide and to engage the aligned grooves in the bottoms of said wedge members by means of the force of a spring disposed in said vertical bore.
 10. The powdered material compacting press as claimed in claim 1, wherein said means responsive to a predetermined amount of descending movement of the platen comprises an unlocking rod slidably passing vertically through said wedge driving member and resiliently urged upward to extenD above the upper surface of the platen from which the wedge driving member projects downward, the upper end of said unlocking rod being adapted to be depressed by a platen immediately thereabove and the lower end of said unlocking rod being in connection with said means for locking the wedge member.
 11. The powdered material compacting press as claimed in claim 9, wherein said means responsive to a predetermined amount of descending movement of the platen comprises an unlocking rod slidably passing vertically through said wedge driving member and resiliently urged upward to extend above the upper surface of the platen from which the wedge driving member depends, the upper end of said unlocking rod being adapted to be depressed by a platen immediately thereabove and the lower end of said unlocking rod being in abutment with the upper end of said locking key member.
 12. The powdered material compacting press as claimed in claim 11, wherein said unlocking rod is resiliently urged by means of a compression spring disposed in a hollow interior of said wedge driving member and acting upward on a flange formed on said unlocking rod. 